1. Field of the Invention
The present invention relates to a system for auditing the contents of library elements capable of holding storage cartridges in an automated library.
2. Description of the Related Art
An automated information storage and retrieval system, also known as an automated library, includes an array of storage cells, i.e., storage slots, that hold storage cartridges, such as optical disks or magnetic tapes that are portable and removable from the library. The term "storage cartridge" as used herein refers to any structure for housing such removable information media. The library further includes one or more drives to read information from the storage cartridges located in the storage cells.
FIG. 1 illustrates an automated library 2, such as the International Business Machines Corporation ("IBM.RTM.") 3995 Optical Library Dataserver, which is described in IBM publication "3995 ECKD Storage Administration Guide", document no. GA32-0242-02 (IBM Copyright, 1994), which publication is incorporated herein by reference in its entirety. A similar automated library system is described in U.S. Pat. No. 5,652,742, entitled "Cartridge Retention in Storage Cell Arrays," assigned to IBM, the assignee of the subject patent application, which patent is incorporated herein by reference in its entirety.
The library 2 includes a controller, an input/output station, a picker assembly 4, a carriage assembly 6, storage cells 8a, b, and optical disk drives (not shown). The term "library element" as used herein refers to any slot in the automated library 2 in which storage cartridges may be disposed, e.g., the input/output stations, the storage cells 8a, b, the disk drives, etc. The library controller includes a processor, RAM, and other controls and interfaces to direct the actions of the library components. The controller further interacts with a host processor to respond to library commands transmitted from the host processor. The input/output station is the opening through which the user may insert or remove a cartridge. An operator panel on the outside of the box housing the tape library allows the user to communicate with the library controller. When adding a cartridge through the input/output slot, the user may indicate the addition of a cartridge using the operator panel. The library 2 also includes an access door 12 through which the user may add or remove cartridges maintained in the storage cells 8a, b.
The library 2 has two columns of storage cells 8a, b and optical disk drives 10a, b that perform read and write operations with respect to the storage cartridges. A picker assembly 4 is capable of manipulating the storage cartridges in the library elements. A carriage assembly 6 moves the picker assembly 4, and any cartridge held by the picker assembly 4, among the library elements. The carriage assembly 6 transports the picker assembly 4 to a destination library element. The picker assembly 4 can rotate to turn the cartridge over. The picker assembly 4 has a finger mechanism to remove or insert a storage cartridge to a library element. Once inserted in the drive 10a, b, data can be read from the cartridge and sent to a host processor. Data transmitted from the host processor can be written to the storage cartridge inserted in the drive 10a, b.
The picker assembly 4 may also be equipped with a machine vision system, such as a bar code reader, to read a label on the cartridge when the picker assembly 4 is positioned near a library element. During an inventory of the library, such as when a new library is installed, the machine vision system scans the library elements. The machine vision system then informs the library controller of the identity of the stored cartridges and their location in the library elements. Alternatively, in a library without a vision system, each cartridge must be loaded into a drive 10a, b in order to read cartridge identifier information stored within the cartridge. After reading the identifying information, the storage cartridge is returned to the originating library element. The library controller records the identity and location information in a database to "know" the contents of each storage cell and the identity and location of the storage cartridges within the array of library elements.
An audit of the storage cartridges in library elements updates information in a cartridge map indicating the contents of the library elements. The cartridge map is stored in a memory accessible to the library controller. To audit the contents of the library elements, the library controller directs the machine vision system, if available, to first determine whether the library elements are empty. The library controller would then direct the machine vision system to read the label on the storage cartridge in the library element. The library controller would then update the cartridge map to reflect the current status of the library elements determined during the audit. This auditing process often takes several minutes. If the library 2 does not include machine vision equipment for reading the cartridges, then the audit is even more time consuming because each cartridge must be loaded into a drive 10a, b to obtain information on the contents of the storage cartridge before updating the cartridge map with the current information on that cartridge.
Typically, an inventory of the entire array of library elements must be taken whenever the library operator opens the access door 12, even if the operator did not alter the contents of any library element in the array. In the current art, the system "assumes" that all library elements have been altered whenever the access door is opened.